1. Field
The present disclosure relates to thin-film transistors (TFTs) that may be used as a more efficient switching device and methods of manufacturing the TFTs.
2. Description of the Related Art
Thin-film transistors (TFT) are utilized in various fields and are frequently used as switching devices and driving devices in display apparatuses. TFT performance may be significantly affected by characteristics of the material constituting a channel layer, through which charge carriers move. Thus, TFTs made of various materials are being developed and analyzed. Examples of TFTs used as switching devices and driving devices in display apparatuses include an amorphous silicon TFT (a-Si TFT), a poly-crystal silicon TFT (poly-Si TFT), and an oxide TFT.
An a-Si TFT is the most commonly used TFT in display apparatuses, because an a-Si TFT may be uniformly formed on a relatively large substrate of over 2 meters with relatively low cost. However, as display apparatuses become larger and have higher resolutions, higher performance is being demanded of TFTs. Thus, attempts have been made to use materials having higher levels of mobility as channel layers.
A poly-Si TFT is significantly more efficient than a-Si TFT and has higher mobility (e.g., from about dozens of cm2/Vs to hundreds of cm2/Vs). Thus, a poly-Si TFT is efficient enough to be used for a higher resolution display apparatus. However, the fabrication of a poly-Si TFT requires relatively complex operations and additional costs as compared to the fabrication of an a-Si TFT. In addition, uniformity of poly-Si TFT decreases when a poly-Si TFT is applied to a relatively large substrate.
On the other hand, an oxide TFT has advantages of both an a-Si TFT and a poly-Si TFT. As a result, there has been an increased focus on developing oxide TFTs. In addition to an oxide TFT exhibiting relatively high mobility characteristics, a channel layer thereof may be formed by using a direct deposition method instead of using laser. Thus, even when an oxide TFT is applied to a relatively large area substrate, satisfactory performance may be expected.